Proper cable sizing requires balancing current-carrying capacity (ampacity), voltage drop, and environmental factors. 1. Determine the Electrical Load The first step is to calculate the design current ( Ibcap I sub b
Cable sizing tables or calculators are available from cable manufacturers or online resources. These tables or calculators take into account the load requirements, cable type, and ambient temperature to provide the minimum cable size required. how to size a cable
| Copper, XLPE, 90°C, 30°C ambient, free air | 1.5 mm² → 24 A | 2.5 mm² → 32 A | 4 mm² → 42 A | | Aluminum, PVC, 70°C, buried | 16 mm² → 70 A | etc. | These tables or calculators take into account the
The cable must have a base rating ($I_z$) that, after derating, is still higher than the protective device rating ($I_n$). : 400 V three-phase motor, 22 kW, cosφ=0
: 400 V three-phase motor, 22 kW, cosφ=0.86, η=0.92. Length = 120 m. Installation: PVC cable in conduit on wall with 3 other circuits, ambient 40°C. Protection: C-curve MCB, Isc = 5 kA.